n serious | Seriousness; reality; actuality (as opposed to jesting or feigned appearance); fixed determination; eagerness; intentness.
a ardent | Ardent in the pursuit of an object; eager to obtain or do; zealous with sincerity; with hearty endeavour; heartfelt; fervent; hearty; — used in a good sense; as, 'earnest' prayers.
a serious | Serious; weighty; of a serious, weighty, or important nature; not trifling or feigned; important.
n A sum of money paid in advance as a deposit; hence, a pledge, a guarantee, an indication of something to come.